1. Field of the Invention
The present invention is directed to a data inputting and outputting method to a peripheral devices in a computer system operating with a plurality of operating systems on a single processor, and is related to a control method for using the same peripheral device in common for a plurality of operating systems in common.
2. Description of the Related Art
In normal computer, one operating system is operated. The operating system manages resources of the computer, such as a processor, a memory and a secondary storage device and performs resource scheduling so as to operate the computer efficiently. Here, there are various kinds of operating systems. One is superior in batch process, another is superior in GUI such as an office work, the other is superior in a real time process. In order to bring out feature of a plurality of operating systems, there is a needs to execute a plurality of operating systems simultaneously on the single computer. For example, in case of a large size computer, it has been demanded to operate an operating system executing an on-line process associated with an actual business or an operating system for development. Also, it is demanded to operate an operating system provided with GUI and an operating system superior in real time characteristics.
As a mechanism for operating a plurality of operating systems on one computer, there is a virtual computer system (OS Series Vol. 11, VM, Tomoo OKAZAKI, Kyoritsu Shuppan K.K.) which has been realized in a large size computer, in the virtual computer system. A virtual computer control program occupies and manages all hardware and make it virtual to form the virtual computer. A control portion forming the virtual computer makes a physical memory, an input and output device, an external interrupt and so forth virtual. For example, divided physical memory behave as if a physical memory starting from zero address for the virtual computer. Unit numbers identifying the input and output device are also made virtual. Furthermore, by dividing a storage region of a magnetic disk to realize even making a magnetic disk drive virtual.
On the other hand, as a technology for providing interface for a plurality of operating system in one computer, there is a micro kernel. In the micro kernel, an operating system server for providing operating system function to be shown to the user on micro kernel, is established. The user utilizes a resource of the computer via the server. By providing servers for each operating system, it becomes possible to provide various operating system environments for the user.
For example, in case of a vehicle mounting navigation system, importance is given for a real time characteristics for instantly responding to variation of external environment and a reliability as to not to stop the system. Therefore, a real time operating system (real time OS) having a compact module construction with high interruption response is frequently used. However, the real time OS cannot be said to have superior interface with a person, while it gives importance for real time characteristics and reliability. On the other hand, an office work operating system (general purpose OS) to be typically used in typical personal computer (PC) is provided an environment for directly operating a display, such as GUI to provide superior human interface. Therefore, a demand to use a user interface of the general purpose OS even in the field where the real time OS has been used conventionally, is growing. However, since the general purpose OS takes interactive process with the person, it gives greater importance for a throughput of the process rather than response characteristics to interrupt process and thus is possible to execute a process with maintaining interrupt inhibiting condition for a relatively long period. On the other hand, in comparison with the real time OS having compact construction, it cannot be said comparable in reliability.
However, similarly to a system for operating a plurality of virtual computers (operating systems) in parallel on the large size computer, if the general purpose OS and the real time OS can be operated in the same computer system in a build-in system to switch the operating system as required, it may be possible to achieve both of superior used interface and real time characteristics and reliability. Considering improvement of performance of the microprocessor, operating a plurality of operating systems in one computer system has not been a technology permitted only the large size computer.
While it is required to be adapted for multiple users in the large computer, whereas a built-in equipments may be required to be at least adapted to a single user in the build-in equipments. Therefore, when the real time OS and the general purpose OS are operated in the single system, a simplest operating system switching method in consideration of importance of respective operating systems, if a process to be executed in the real time OS is present, to operate the real time OS preferentially and to operate the general purpose OS when the task to be executed on the real time OS is not present, is applicable. In such switching method the operating systems, a method of switching of the operating system by discriminating the interrupt number generated, by statically determining the operating system receiving the interrupt demand per input and output devices in inputting and outputting with the peripheral device. For example, when the foregoing method is applied to the vehicle mounted navigation system, the operating system is switched so that an interrupt handler of the real time OS is actuated for the interrupt from the sensor necessary for determining the position and an interrupt handler of the general purpose OS is actuated for interrupt from a display controller. However, since the reliability of the general purpose OS is not necessarily high, in the shown application, process of the general purpose OS is stopped, the user interface becomes impossible to use to lower reliability of the overall vehicle mounted navigation system. In order to solve the foregoing problem, the process may be divided to assign the process which is desired to never be interrupted to the real time OS side and to assign the process permitting interruption to the general purpose OS side. However, if the input and output process for the user interface is process on the side of the real time OS, introduction of the general purpose OS superior in user interface becomes meaningless. Therefore, it becomes essential to permit use of the input and output device from a plurality of operating systems, namely from both of the general purpose OS and the real time OS. Therefore, a problem is encountered in that it is insufficient to statically determine the operating system to execute the input and output process from the interrupt number as set forth above, and cannot be applicable for practical use.
An object of the present invention to provide a scheme to making the input and output device provided in a computer in common for a plurality of operating system, in a multiple operating system control unit operating a plurality of mutually distinct operating systems on one computer system.
In order to accomplish the above mentioned object, According to the first invention, a computer system including a plurality of operating systems, and an OS switching means for switching a plurality of operating systems, characterized in that said OS switching means makes reference to a preferential interrupt table on the basis of an interrupt factor for switching to corresponding operating system and calls interrupt processing means incorporated in said operating system for making the input and output device provided in the computer system in common for a plurality of operating systems.
According to the second invention, a computer system having a plurality of operating systems and OS switching means for switching a plurality of operating systems, characterized by including peripheral device to be common for a plurality of operating systems, data inputting and outputting server for inputting and outputting data with the peripheral device to be used in common, providing in one of the operating systems, data inputting and outputting client for inputting and outputting data with the operating system other than said one operating system, requesting inputting and outputting data to said data inputting and outputting server and executing inputting and outputting of data by receiving a result of data inputting and outputting with the peripheral server in the data inputting and outputting server.